When a liquid filter—e.g., a fuel filter for diesel fuel—is in operation, the delivery of unpurified liquid to the internal combustion engine when a filter element has been removed must be avoided.
EP 1 937 962 B1 therefore proposes providing a slide valve in an upper region of the filter housing, with a through opening that is positioned when a filter element has been inserted so as to be aligned to a through opening on a housing-fixed central tube.
Also known, however, are filter systems without a housing-fixed central tube, where filter elements comprising element-side central tubes are used instead. Such filter systems are described in, for example, WO 2014/191486 A1.